3d target for monitoring multiple patterning process

ABSTRACT

A metrology target is designed for monitoring variations in a multiple patterning process, such as a self-aligned doubled patterning (SADP) or self-aligned quadruple patterning (SAQP) process. The metrology target may include a plurality of sub-patterns. For example, the metrology target may be a three-dimensional (3D) target rather than a conventional two-dimensional line-space target design. The 3D target design includes multiple sub-patterns arranged with a pitch in a direction that is different than the pitch of the lines and trenches. The pitch of the sub-patterns is sufficient so that multiple sub-patterns are simultaneously within the field of measurement.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims under 35 USC §119 the benefit of and priority toU.S. Provisional Application No. 62/199,612, filed Jul. 31, 2015,entitled “3D Target for Monitoring Multiple Patterning Process,” whichis assigned to the assignee hereof and is incorporated herein byreference.

BACKGROUND

Background Field

Embodiments of the subject matter described herein are related generallyto optical metrology targets, and more particularly to target design andmanufacture for monitoring a multiple patterning process.

Relevant Background

As critical dimensions (CD) in semiconductor devices continue to shrink,the use of multiple patterning has become an important method. Multiplepatterning processes, such as self-aligned doubled patterning processand self-aligned quadruple patterning process, is a technology that isused to extend photolithography beyond diffraction limit therebyenhancing feature density. As the name implies, multiple patterningprocesses include more than one patterning process step. For example,self-aligned doubled patterning process includes two patterning processsteps: a lithography patterning step and a self-aligned spacer step.Self-aligned quadruple patterning process typically includes threepatterning process steps: lithography patterning, a first self-alignedspacer step and a second self-aligned spacer step. Each of thepatterning process steps in a multiple patterning process willcontribute to the final critical dimension uniformity and CDdistribution within the printed structure. To control the process and toachieve optimum CD distribution, it is necessary to determine thecontribution of each patterning step to the final CD variation.

SUMMARY

A metrology target is designed for monitoring variations in a multiplepatterning process, such as a self-aligned doubled patterning (SADP) orself-aligned quadruple patterning (SAQP) process. The metrology targetmay include a plurality of sub-patterns. For example, the metrologytarget may be a three-dimensional (3D) target rather than a conventionaltwo-dimensional line-space target design. The 3D target design includesmultiple sub-patterns arranged with a pitch in a direction that isdifferent than the pitch of the lines and trenches. The pitch of thesub-patterns is sufficient so that multiple sub-patterns aresimultaneously within the field of measurement of the metrology device.

In one implementation, a metrology target on a wafer for monitoring amultiple patterning process comprises a plurality of orthogonallyarranged lines and trenches produced with the multiple patterningprocess producing a plurality of sub-patterns having a first pitch in afirst direction and, wherein the lines and trenches in each sub-patternhave a second pitch that is in a second direction that is different thanthe first direction, wherein the orthogonally arranged lines in eachsub-pattern produces two sets of a first box, with a trench disposedwithin the first box and a second trench between the two sets, andwherein the first pitch and the second pitch of the plurality ofsub-patterns are configured so that there are a plurality ofsub-patterns within a field of measurement of a metrology device.

In one implementation, a method of manufacturing a metrology target on awafer for monitoring a multiple patterning process, comprises performinga lithography patterning step to pattern a set of resist for themetrology target, wherein, the set of resist for the metrology target ispatterned with a first pitch in a first direction and a second pitch ina second direction that is different than the first direction; andperforming etching processes and at least a first self-aligned spacerprocess to produce the metrology target comprising a plurality oforthogonally arranged lines and trenches producing a plurality ofsub-patterns having a third pitch in the first direction and, whereinthe lines and trenches in each sub-pattern have a fourth pitch in thesecond direction, wherein the orthogonally arranged lines in eachsub-pattern produces two sets of a first box, with a trench disposedwithin the first box and a second trench between the two sets, andwherein the first pitch and the second pitch of the plurality ofsub-patterns are configured so that there are a plurality ofsub-patterns within a field of measurement of a metrology device.

In one implementation, a method of monitoring a multiple patterningprocess comprises producing a metrology target on a wafer with themultiple patterning process, the metrology target comprising a pluralityof orthogonally arranged lines and trenches producing a plurality ofsub-patterns having a first pitch in a first direction, wherein thelines and trenches in each sub-pattern have a second pitch that is in asecond direction that is different than the first direction, wherein theorthogonally arranged lines in each sub-pattern produces two sets of afirst box, with a trench disposed within the first box and a secondtrench between the two sets; producing illumination with an opticalmetrology device that is focused into a field of measurement on themetrology target, wherein the first pitch and the second pitch of theplurality of sub-patterns are configured so that there are a pluralityof sub-patterns within the field of measurement of the optical metrologydevice; collecting scatterometry data with the optical metrology devicefrom the illumination scattered from the metrology target within thefield of measurement; and analyzing the scatterometry data from themetrology target to monitor the multiple patterning process, wherein theanalysis of the scatterometry data produces the dimension andregistration of the plurality of orthogonally arranged lines andtrenches in the metrology target.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1H illustrate cross sectional views of a typical multiplepatterning process.

FIG. 2 illustrates cross-sectional views of three patterning processsteps in self-aligned quadruple patterning (SAQP) process along with theresulting device.

FIGS. 3A, 3B, and 3C are graphs illustrating the impact of each processstep in FIG. 2 on CD variations.

FIG. 4 illustrates a top view of a conventional two-dimensional (2D)line-space device resulting from an SAQP process.

FIG. 5 illustrates a top view of a sub-pattern that may be used in athree-dimensional (3D) metrology target for monitoring the SAQP process.

FIG. 6 illustrates the lithography patterning step used in the SAQPprocess to produce the sub-pattern of FIG. 5.

FIG. 7 is a top view of a 3D metrology target including a repeatingpattern of sub-patterns, which may be used for monitoring the SAQPprocess.

FIG. 8 illustrates top views of a standard 2D design target, and twocomparable 3D design targets with different pitches along the length.

FIG. 9 is a graph illustrating a comparison of the simulated precisionof the standard targets illustrated in FIG. 8.

FIG. 10 illustrates a top view of a sub-pattern that may be used in athree-dimensional (3D) metrology target for monitoring the self-aligneddoubled patterning (SADP) process.

FIG. 11 illustrates a top view of a sub-pattern that may be used in athree-dimensional (3D) metrology target for monitoring the self-alignedtriple patterning (SATP) process.

FIG. 12 illustrates a top view of a sub-pattern that may be used in athree-dimensional (3D) metrology target for monitoring the self-alignedoctuple patterning (SAOP) process.

FIG. 13 illustrates a schematic view of an optical metrology device thatmay be used to collect and analyze scatterometry data from metrologytargets to monitor a multiple patterning process.

FIG. 14 is a flow chart illustrated a method of manufacturing ametrology target on a wafer for monitoring a multiple patterningprocess.

FIG. 15 is a flow chart illustrated a method of monitoring a multiplepatterning process.

DETAILED DESCRIPTION

In accordance with an embodiment of the present invention, scatterometrytechniques and designed targets may be used to measure the CD variationin the final step of a multiple patterning process, such as self-aligneddoubled patterning (SADP) process, self-aligned triple patterning(SATP), self-aligned quadruple patterning (SAQP) process, orself-aligned octuple patterning (SAOP). The targets discussed herein maybe located within scribe lines between chips or may be located withinthe chips, e.g., in active areas of the chips. The metrology target mayhave a three-dimensional (3D) design, rather than the conventionaltwo-dimensional (2D) line-space design. By way of example, theconventional line-space target design for measuring multiple patterningprocess, such as SAQP process, have high measurement uncertainty as itis difficult to correlate individual line and spaces to a particularpatterning step. With the use of the 3D target, the deficiencies of aconventional 2D target are overcome.

FIGS. 1A-1H illustrate cross sectional views of a typical multiplepatterning process, such as SADP or SAQP. As illustrated in FIG. 1A, adevice 100 includes a film 102 (or substrate) with three hard masklayers (HM1, HM2, and HM3) and intervening dielectric layers 104overlying the film 102. In an SADP process, the hard mask HM3 andoverlying dielectric layer would not be present. FIG. 1A illustrates thelithography patterning step in which resist 106 is patterned in a lineover the top dielectric layer 104. By way of example, the resist 106line may have a width W of 45 nm, and there may be a space S of 75 nmbetween the resist 106, producing a pitch P of 120 nm. FIG. 1Billustrates the device after etching the hard mask HM1, leaving hardmask HM1 only under areas protected by resist 106. FIG. 1C illustratesthe device after the first self-aligned spacer step, including the firstspacer deposition and anisotropic etch, resulting in spacers 1. Thespacers 1, by way of example, may have a width of 15 nm. FIG. 1Dillustrates the device after etching the remaining hard mask HM1 leavingspacers 1. FIG. 1E illustrates the device after etching the hard maskHM2, leaving hard mark HM2 only under areas protected by spacers 1. In aSADP process, the process would be finished after the etching of thehard mask HM2 as shown in FIG. 1E (and the hard mask HM3 and overlyingdielectric layer would not be present). In the SAQP, the processcontinues, as illustrated in FIG. 1F. FIG. 1F illustrates the deviceafter the second self-aligned spacer step, including the second spacerdeposition and anisotropic etch, resulting in spacers 2. The spacers 2,by way of example, may have a width of 15 nm. FIG. 1G illustrates thedevice after etching the remaining hard mask HM2 leaving spacers 2. FIG.1H illustrates the resulting device after etching the hard mask HM3,leaving hard mark HM3 only under areas protected by spacers 2. Theresulting device, for example, includes a number of lines having widthsof 15 nm and trenches having widths 15 nm, resulting in a pitch of 30nm.

FIG. 2, by way of example, illustrates the impact of the differentpatterning steps on the resulting trenches in a multiple patterningprocess. Specifically, FIG. 2 illustrates cross-sectional views of thethree patterning process steps in the SAQP process along with theresulting device, with dotted, dashed, and dash-dotted linesillustrating the impact of the different patterning steps on theresulting trenches. Thus, FIG. 2 illustrates the lithography patterningstep 150 (also shown in FIG. 1A), the first self-aligned spacer step 152(shown in FIG. 1C), and the second self-aligned spacer step 154 (shownin FIG. 1F), along with the resulting device 156 (shown in FIG. 1H).FIG. 2 illustrates the alignment of trenches labeled A with dottedlines, the alignment of trenches labeled B with dashed lines, and thealignment of trenches labeled C with dashed dotted lines. As can be seenin FIG. 2, the width and location of trenches are dependent on thelithography patterning step 150, the first self-aligned spacer step 152,and the second self-aligned spacer step 154.

FIGS. 3A, 3B, and 3C are graphs illustrating the impact of each processstep on CD variations in the SAQP process. For example, FIG. 3A is agraph illustrating the impact of variation in the lithography CD on thetrench CD. As can be seen in FIG. 3A, when the CD in the lithographystep is larger, i.e., the width W of the resist in FIG. 1A is larger,the width of trench B is constant, the width of trench A will increaseand the width of trench C is smaller.

FIG. 3B illustrates the impact of variation in the first self-alignedspacer step 152 on the trench CD. As can be seen in FIG. 3B, when the CDin the first self-aligned spacer step 152 is larger, i.e., when thewidth of spacers 1 in FIG. 1C is larger, the width of trench A remainsconstant, the width of trench B increases and the width of trench Cdecreases twice as fast.

FIG. 3C illustrates the impact of variation in the second self-alignedspacer step 154 on the trench CD. As can be seen in FIG. 3C, when the CDin the second self-aligned spacer step 154 is larger, i.e., when thewidth of spacers 2 in FIG. 1F is larger, the width of trench B remainsconstant and the width of both trenches A and C decreases twice as fast.

To monitor a multiple patterning process, a 3D target design may be usedin place of the conventional 2D line-space targets. FIG. 4, by way ofexample, illustrates a top view of a conventional 2D line-space target300, including lines 302 and trenches 304, resulting from a SAQPprocess. Target 300 is referred to as two-dimensional, as the linesextend well beyond the field of measurement of a metrology devicemeasuring the target 300, and thus, only the width and height dimensionsof the lines and trenches are viewed. While the trenches 304 areillustrated in FIG. 4 with different hash marks to clearly identify thedifferent trenches, in the traditional 2D line-space target 300 all ofthe resulting trenches are nearly identical, making it difficult todetermine the registration of the trenches, which is necessary tomonitor the process of each patterning step. Moreover, typically withinthe chip, there are a large number of line/space patterns that are sideby side. Accordingly, within the field of measurement of the metrologydevice the targets appear as a grating with, e.g., 400 sets within a 40μm spot. Accordingly, one assignment 310 of the trench registration,illustrated with the solid frame, will appear to be as valid as analternative assignment 320, illustrated with a dashed frame. Any attemptto drastically change the width of an individual trench to helpdistinguish the registration, however, will result in the target beingnot compatible with the process.

FIG. 5 illustrates a top view of a portion of the metrology target 400(sometimes referred to as a sub-pattern) for monitoring the SAQPprocess. As can be seen, the portion of the metrology target 400 has a3D design with two sets of lines 402 and 404, and intervening spaces406, 408, and 410. The lines 402 and 404 extend in both the X directionand the Y direction to form boxes. The length of the lines 402, i.e., inthe X direction is less than the field of measurement of the metrologydevice measuring the target 400, and thus, the length, width and heightdimensions of the lines and trenches are viewed. With 3D design of thetarget 400, e.g., with the lines 402 and 404 forming boxes, theregistration of the spaces is easily assigned, as indicated in FIG. 5.Moreover, the pattern also has the benefit of better compatibility tothe multiple patterning process as it requires no cut mask, i.e., noextra step.

Thus, the orthogonally arranged lines and trenches in the target 400produces two sets of a first box within a second box, with a firsttrench A (410) disposed within the first box formed with lines 404,second trenches B (408) disposed between the first box formed with lines404 and the second box formed with lines 402, and a third trench C (406)between the two sets.

FIG. 6 illustrates the lithography patterning step used in the SAQPprocess to produce the target 400. As illustrated in FIG. 6, during thelithography process, target 400 is produced with resist 412 having alength L, which is significantly short than the length of the lines usedin the actual device. The remaining parameters, e.g., width W, space S,and pitch P may be the same as used in the actual device. If desired,however, one or more variations may be included in the remainingparameters.

FIG. 7 is a top view of the metrology target 400, which as can be seenhas a repeating pattern of sub-patterns, which may be used formonitoring the SAQP process. Thus, the metrology target has a firstpitch in a first direction (X axis) and the plurality of sub-patternshas a second pitch in a second direction (Y axis) that is different thanthe first direction. Additionally, in FIG. 7, the field of measurement420 of the metrology device is illustrated with a dashed line. As can beseen in FIG. 7, the target 400 has a pitch in the second direction thatis configured so that the sub-patterns repeat several times within thefield of measurement 420, so that both ends along the length ofsub-patterns can be seen within the field of measurement 420. In oneexample, the target 400 may have sub-patterns that repeat five times ormore within the field of measurement 420. The target 400 may also have apitch in the first direction that is also configured so that thesub-patterns repeat several times within the field of measurement 420,so that both ends along the width of sub-patterns can be seen within thefield of measurement 420.

FIG. 8 illustrates top views of a standard 2D design target 500, withe.g., 96 nm pitch, and a comparable 3D design target 502 with a 96nm×192 nm pitch, and another comparable 3D design target 504 with a 96nm×384 nm pitch. FIG. 9 is a graph illustrating a comparison of thesimulated 3sigma precision (i.e., the 3 times the standard deviation ofa set of data) of the standard 2D design target 500 and the 3D designtargets 504 and 506, where “Fin” indicates the channel formation of aFinFET device, “SWA” is sidewall angle, “HT” is height, “Space A” is thewidth of Space A, e.g., as identified in FIGS. 4 and 5, “BCD” is thebottom critical dimension, and “Space B” is the width of Space B, e.g.,as identified in FIGS. 4 and 5. As can be seen, in addition to thecapability of assigning trench registration, the 3D design targets 502and 504 also improve the precision for OCD measurement, by more than anorder of magnitude for the widths of space A and space B.

With the use of the 3D design target, metrology is simplified as theline and spaces created by multiple process steps are different fromeach other in shape and dimension, and therefore the registration can beeasily assigned. With the proper assignment of the trench registration,the scatterometry data obtained from the 3D design target may beprocessed and analyzed in a conventional manner. The scatterometry datamay be analyzed, e.g., using modeling, such as Rigorous Coupled WaveAnalysis (RCWA) based scatterometry, to determine any variations presentin the multiple patterning process.

While the SAQP process is specifically addressed by the target designshown in FIGS. 5-9, it should be understood that other multiplepatterning processes may be monitored using similarly 3D designedtargets. For example, FIG. 10 illustrates a top view of a portion of themetrology target 450 (sometimes referred to as a sub-pattern) formonitoring the SADP process. As illustrated, the sub-pattern 450includes orthogonally arranged lines that produce two sets of boxes,with a trench disposed within the boxes and a trench between the twosets of boxes. As discussed with sub-pattern 400, the pitch of theplurality of sub-patterns 450 is configured so that there is a pluralityof sub-patterns within a field of measurement of a metrology device.

FIG. 11 illustrates a top view of a portion of the metrology target 460(sometimes referred to as a sub-pattern) for monitoring the self-alignedtriple patterning (SATP) process. As illustrated, the sub-pattern 460includes orthogonally arranged lines that produce two sets of boxes,with a line disposed in a box and a trench disposed between the line andthe box, and a trench between the two sets of boxes. As discussed withsub-pattern 400, the pitch of the plurality of sub-patterns 460 isconfigured so that there is a plurality of sub-patterns within a fieldof measurement of a metrology device.

FIG. 12 illustrates a top view of a portion of the metrology target 470(sometimes referred to as a sub-pattern) for monitoring the self-alignedoctuple patterning (SAOP) process. As illustrated, the sub-pattern 470includes orthogonally arranged lines that produce two sets of nestedboxes, each set includes four nested boxes with trenches disposedbetween each box and between the sets. As discussed with sub-pattern400, the pitch of the plurality of sub-patterns 470 is configured sothat there is a plurality of sub-patterns within a field of measurementof a metrology device.

FIG. 13, by way of example, illustrates a schematic view of an opticalmetrology device 600 that may be used to collect and analyzescatterometry data from a 3D design metrology target 632 for monitoringa multiple patterning process as discussed above. The metrology device600 includes an optical head 602 coupled to a computer 650, such as aworkstation, a personal computer, central processing unit or otheradequate computer system, or multiple systems, that analyzes the datacollected from the target 632. The optical metrology device 600illustrated in FIG. 13 is, e.g., a spectroscopic reflectometer, but ifdesired, any optical metrology device capable of collectingscatterometry data may be used, such as an ellipsometer. If desired,multiple optical heads, i.e., different metrology devices, may becombined in the same metrology device 600. The computer 650 may alsocontrol the movement of a stage 620 that holds the wafer 630 thatincludes the target 632 via actuators 621 and/or the optical head 602.The stage 620 may be capable of horizontal motion in either Cartesian(i.e., X and Y) coordinates, as indicated by arrows 623 and 624, orPolar (i.e., R and θ) coordinates or some combination of the two. Thestage 620 and/or optical head 602 may also be capable of verticalmotion, e.g., for focusing.

The optical head 602 may include an optical system 604 including abroadband light source 606, such as a Xenon Arc lamp and/or a Deuteriumlamp, and a detector 616, such as a spectrometer. In operation, lightproduced by the light source 606 may be directed along an optical axis608, e.g., via beam splitter 610, toward the wafer 630 which includes atarget 632. An objective 612 focuses the light onto the target 632 andreceives light that is reflected from the target 632. The reflectivelight may pass through the beam splitter 610 and is focused with lens614 onto the detector 616. The detector 616 provides a spectroscopicsignal to the computer 650. The objective 612, beam splitter 610, lens614, and detector 616 are merely illustrative of typical opticalelements that may be used. Additional optical elements, such as apolarizer and/or analyzer, may be used if desired. Moreover, generally,additional optical elements such as field stops, lenses, etc. may bepresent in the optical system 604.

The optical system 604 produces a measurement spot on the target 632,and the detector 616 receives the resulting spectral signal. Thespectral signal from the target 632 may be provided to a computer 650,which additionally has the target models. The computer 650 includes aprocessor 652 with memory 654, as well as a user interface includinge.g., a display 656 and input devices 658. The scatterometry data, alongwith the target models, may be stored at least temporarily in memory 654or in non-transitory computer-usable storage medium 660. Additionally,non-transitory computer-usable storage medium 660 may havecomputer-readable program code embodied thereon and may be used by thecomputer 650 for causing the processor to control the metrology deviceand to perform the functions described herein for analyzing thescatterometry data. The data structures and software code forautomatically implementing one or more acts described in this detaileddescription can be implemented by one of ordinary skill in the art inlight of the present disclosure and stored, e.g., on a computer usablestorage medium 660, which is any non-transitory device or medium thatcan store code and/or data for use by a computer system such asprocessor 652. The computer-usable storage medium 660 may be, but is notlimited to, magnetic and optical storage devices such as disk drives,magnetic tape, compact discs, and DVDs (digital versatile discs ordigital video discs). A communication port 662 may also be used toreceive instructions that are stored in memory 654 or other storage incomputer 650 and used to program the computer 650 to perform any one ormore of the functions described herein and may represent any type ofcommunication connection, such as to the internet or any other computernetwork. Additionally, the functions described herein may be embodied inwhole or in part within the circuitry of an application specificintegrated circuit (ASIC) or a programmable logic device (PLD), and thefunctions may be embodied in a computer understandable descriptorlanguage which may be used to create an ASIC or PLD that operates asherein described. The results from the analysis of the scatterometrydata may be stored, e.g., in memory 654 associated with the wafer 630and/or provided to a user, e.g., via display 656, an alarm or otheroutput device. Moreover, the results from the analysis may be fed backto the process equipment to adjust the appropriate patterning step tocompensate for any detected variances in the multiple patterningprocess.

FIG. 14 is a flow chart illustrated a method of manufacturing ametrology target on a wafer for monitoring a multiple patterningprocess. As illustrated, a lithography patterning step is performed topattern a set of resist for the metrology target (702). The set ofresist for the metrology target is patterned with a first pitch in afirst direction and a second pitch in a second direction that isdifferent than the first direction. An etching processes is performedand at least a first self-aligned spacer process is performed to producethe metrology target comprising a plurality of orthogonally arrangedlines and trenches producing a plurality of sub-patterns having a thirdpitch in the first direction and, wherein the lines and trenches in eachsub-pattern have a fourth pitch in the second direction (704). Theorthogonally arranged lines in each sub-pattern produces two sets of afirst box, with a trench disposed within the first box and a secondtrench between the two sets, and wherein the first pitch and the secondpitch of the plurality of sub-patterns are configured so that there area plurality of sub-patterns within a field of measurement of a metrologydevice.

FIG. 15 is a flow chart illustrated a method of monitoring a multiplepatterning process. As illustrated, the method includes producing ametrology target on a wafer with the multiple patterning process (802).The metrology target includes a plurality of orthogonally arranged linesand trenches producing a plurality of sub-patterns having a first pitchin a first direction, wherein the lines and trenches in each sub-patternhave a second pitch that is in a second direction that is different thanthe first direction, wherein the orthogonally arranged lines in eachsub-pattern produces two sets of a first box, with a trench disposedwithin the first box and a second trench between the two sets.Illumination is produced with an optical metrology device that isfocused into a field of measurement on the metrology target (804),wherein the first pitch and the second pitch of the plurality ofsub-patterns are configured so that there are a plurality ofsub-patterns within the field of measurement of the optical metrologydevice. Scatterometry data is collected with the optical metrologydevice from the illumination scattered from the metrology target withinthe field of measurement (806). The scatterometry data from themetrology target is analyzed to monitor the multiple patterning process,wherein the analysis of the scatterometry data produces the dimensionand registration of the plurality of orthogonally arranged lines andtrenches in the metrology target (808). Analyzing the scatterometry datamay be performed using a model of the metrology target that isregistered with the plurality of orthogonally arranged lines andtrenches in the metrology target.

The multiple patterning process described above may be, for example, aself-aligned doubled patterning (SADP) process. The multiple patterningprocess may be a self-aligned quadruple patterning (SAQP) process,wherein the method further includes performing a second self-alignedspacer process to produce the metrology target, wherein the orthogonallyarranged lines in each sub-pattern further produces the two setsincluding a second box, wherein the first box is within the second box,and a third trenches disposed between the first box and the second box.The multiple patterning process may be a self-aligned triple patterning(SATP) process, and wherein the 3D arranged lines in each sub-patternfurther produces a line within the first box, wherein the trenchdisposed within the first box is between the line and the first box. Themultiple patterning process may be a self-aligned octuple patterning(SAOP) process, and wherein the 3D arranged lines in each sub-patternfurther produces the two sets including a second box, a third box, and afourth box, wherein the first, second third, and fourth boxes are nestedand trenches are disposed between the first, second, third, and fourthboxes. The first pitch and the second pitch of the plurality ofsub-patterns may be configured so that there are at least fivesub-patterns within the field of measurement of the metrology device.

Although the present invention is illustrated in connection withspecific embodiments for instructional purposes, the present inventionis not limited thereto. Various adaptations and modifications may bemade without departing from the scope of the invention. Therefore, thespirit and scope of the appended claims should not be limited to theforegoing description.

What is claimed is:
 1. A metrology target on a wafer for monitoring a multiple patterning process, the metrology target comprising: a plurality of orthogonally arranged lines and trenches produced with the multiple patterning process producing a plurality of sub-patterns having a first pitch in a first direction and, wherein the lines and trenches in each sub-pattern have a second pitch that is in a second direction that is different than the first direction, wherein the orthogonally arranged lines in each sub-pattern produces two sets of a first box, with a trench disposed within the first box and a second trench between the two sets, and wherein the first pitch and the second pitch of the plurality of sub-patterns are configured so that there are a plurality of sub-patterns within a field of measurement of a metrology device.
 2. The metrology target of claim 1, wherein the multiple patterning process is a self-aligned doubled patterning (SADP) process.
 3. The metrology target of claim 1, wherein the multiple patterning process is a self-aligned quadruple patterning (SAQP) process, and wherein the 3D arranged lines in each sub-pattern further produces the two sets including a second box, wherein the first box is within the second box, and a third trenches disposed between the first box and the second box.
 4. The metrology target of claim 1, wherein the multiple patterning process is a self-aligned triple patterning (SATP) process, and wherein the 3D arranged lines in each sub-pattern further produces a line within the first box, wherein the trench disposed within the first box is between the line and the first box.
 5. The metrology target of claim 1, wherein the multiple patterning process is a self-aligned octuple patterning (SAOP) process, and wherein the 3D arranged lines in each sub-pattern further produces the two sets including a second box, a third box, and a fourth box, wherein the first, second third, and fourth boxes are nested and trenches are disposed between the first, second, third, and fourth boxes.
 6. The metrology target of claim 1, wherein the first pitch of the plurality of sub-patterns is configured so that there are at least five sub-patterns within the field of measurement of the metrology device.
 7. A method of manufacturing a metrology target on a wafer for monitoring a multiple patterning process, the method comprising: performing a lithography patterning step to pattern a set of resist for the metrology target, wherein, the set of resist for the metrology target is patterned with a first pitch in a first direction and a second pitch in a second direction that is different than the first direction; and performing etching processes and at least a first self-aligned spacer process to produce the metrology target comprising a plurality of orthogonally arranged lines and trenches producing a plurality of sub-patterns having a third pitch in the first direction and, wherein the lines and trenches in each sub-pattern have a fourth pitch in the second direction, wherein the orthogonally arranged lines in each sub-pattern produces two sets of a first box, with a trench disposed within the first box and a second trench between the two sets, and wherein the first pitch and the second pitch of the plurality of sub-patterns are configured so that there are a plurality of sub-patterns within a field of measurement of a metrology device.
 8. The method of claim 7, wherein the multiple patterning process is a self-aligned doubled patterning (SADP) process.
 9. The method of claim 7, wherein the multiple patterning process is a self-aligned quadruple patterning (SAQP) process, the method further comprising performing a second self-aligned spacer process to produce the metrology target, wherein the orthogonally arranged lines in each sub-pattern further produces the two sets including a second box, wherein the first box is within the second box, and a third trenches disposed between the first box and the second box.
 10. The method of claim 7, wherein the multiple patterning process is a self-aligned triple patterning (SATP) process, and wherein the 3D arranged lines in each sub-pattern further produces a line within the first box, wherein the trench disposed within the first box is between the line and the first box.
 11. The method of claim 7, wherein the multiple patterning process is a self-aligned octuple patterning (SAOP) process, and wherein the 3D arranged lines in each sub-pattern further produces the two sets including a second box, a third box, and a fourth box, wherein the first, second third, and fourth boxes are nested and trenches are disposed between the first, second, third, and fourth boxes.
 12. The method of claim 7, wherein the first pitch and the second pitch of the plurality of sub-patterns are configured so that there are at least five sub-patterns within the field of measurement of the metrology device.
 13. A method of monitoring a multiple patterning process, the method comprising: producing a metrology target on a wafer with the multiple patterning process, the metrology target comprising a plurality of orthogonally arranged lines and trenches producing a plurality of sub-patterns having a first pitch in a first direction, wherein the lines and trenches in each sub-pattern have a second pitch that is in a second direction that is different than the first direction, wherein the orthogonally arranged lines in each sub-pattern produces two sets of a first box, with a trench disposed within the first box and a second trench between the two sets; producing illumination with an optical metrology device that is focused into a field of measurement on the metrology target, wherein the first pitch and the second pitch of the plurality of sub-patterns are configured so that there are a plurality of sub-patterns within the field of measurement of the optical metrology device; collecting scatterometry data with the optical metrology device from the illumination scattered from the metrology target within the field of measurement; and analyzing the scatterometry data from the metrology target to monitor the multiple patterning process, wherein the analysis of the scatterometry data produces the dimension and registration of the plurality of orthogonally arranged lines and trenches in the metrology target.
 14. The method of claim 13, wherein analyzing the scatterometry data comprises using a model of the metrology target that is registered with the plurality of orthogonally arranged lines and trenches in the metrology target.
 15. The method of claim 13, wherein the multiple patterning process is a self-aligned doubled patterning (SADP) process.
 16. The method of claim 13, wherein the multiple patterning process is a self-aligned quadruple patterning (SAQP) process, and wherein the 3D arranged lines in each sub-pattern further produces the two sets including a second box, wherein the first box is within the second box, and a third trenches disposed between the first box and the second box.
 17. The method of claim 13, wherein the multiple patterning process is a self-aligned triple patterning (SATP) process, and wherein the 3D arranged lines in each sub-pattern further produces a line within the first box, wherein the trench disposed within the first box is between the line and the first box.
 18. The method of claim 13, wherein the multiple patterning process is a self-aligned octuple patterning (SAOP) process, and wherein the 3D arranged lines in each sub-pattern further produces the two sets including a second box, a third box, and a fourth box, wherein the first, second third, and fourth boxes are nested and trenches are disposed between the first, second, third, and fourth boxes.
 19. The method of claim 13, wherein the first pitch and the second pitch of the plurality of sub-patterns are configured so that there are at least five sub-patterns within the field of measurement of the optical metrology device. 